The present invention concerns a control device for driving a zoom lens of a camera.
In recent years, as cameras have been designed to be operated electronically and moved electrically, their performance has become higher, and those cameras in which the focal length of the zoom lens can freely be set by one-touch operation from the longest focal length to the shortest focal length have been generally put to practical use. Accordingly, an operator (user) can easily set an angle of view optimum to an intended composition while visually observing an object through a finder. Heretofore, it has been adapted such that the zooming operation is continued for a period during manipulation to a zoom switch for actuating the zooming operation that changes the focal length, while the zooming operation is stopped when the manipulation is interrupted. That is, the operator can visually observe through the finder the image of the object that changes continuously while manipulating the zoom switch and, when an optimum size (view of angle) is attained for the image of the object, stop the manipulation to the zoom switch. Accordingly, a motor for driving the zoom lens has to operate at such a relatively slow speed as enabling the visual observation.
However, depending on the purpose of taking photographs, there is a case that such continuous change for the angle of view is not necessary but rather three finds of focal length, for example, the longest focal length (hereinafter referred to as "TELE position"), the shortest focal length (hereinafter referred to as "WIDE position") and a substantial intermediate position between the WIDE position and the TELE position are generally required and that these positions are intended to be switched rapidly. For instance, in a case of taking a photograph for the whole view of fireworks opening in the night sky or close-up views of individual brilliant points constituting the bursting fireworks until they are extinguished, there is a fear that a shutter chance may be lost by a relatively slow zooming operation as usual and, even if it can be photographed, the view of angle can no more satisfy the aim for the intended composition.
The object of the present invention is to provide a control device for driving a zoom lens of a camera capable of rapid zooming operation for switching the focal length while maintaining the usual operationability in an inexpensive and simple structure.